maybe economics as a single entity yes but there where several studies on agriculture fishing mining trading and so forth that do have an impact on productivity if well used (and one should remember the romans used it well maybe so well that they learnt that slaves where cheaper then labour and above all were expendable)

in a bbc documentary about the worst jobs in the world (link should be in one thread in this forum if not search youtube) they showed how a roman slave was worked to death in the british mines and they explicitly said that the way it was done was to maximize profit (a very important part of economics 101)

also another possible example is in the art of war where one of the 1st chapters talks about making some math and trying to explain the burden of war on a countryes economy (where sun tsu says that a soldier costs 7 families work for a year )

so we can consider that economy wasn´t yet defined but it was already being studied